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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        // 发送AJAX请求，返回一个 Promise 对象
        function sendAJAX(url){

            return new Promise((resolve,reject)=>{
                // 1.创建对象
                const x = new XMLHttpRequest()

                // 2.初始化
                x.open('GET',url)

                // 3.发送
                x.send()

                // 4.事件绑定
                x.onreadystatechange = function(){
                    if(x.readyState === 4){
                        if(x.status >= 200 && x.status <=300){
                            // 成功
                            resolve(x.response)
                        }else{
                            // 失败
                            reject(x.status)
                        }
                    }
                }
            })
        }

        // promise then测试
        // sendAJAX("https://api.apiopen.top/getJoke").then(value=>{
        //     console.log(value);
        // },reason=>{})
        
        // async 与 await 测试
        async function main(){
            // 发送AJAX请求
            let result = await sendAJAX("http://ajax-api.itheima.net")
            console.log(result);
        }

        main()

    </script>
</body>
</html>